U.S. patent application Ser. No. 2002/0190661, by Duggal et al., published Dec. 19, 2002, discloses an organic light emitting diode (OLED) light source that comprises a plurality of OLEDs that are arranged in a plurality of groups. The OLEDs in a group are electrically connected in series, and the groups are electrically connected in parallel. This arrangement is referred to herein as a Parallel/Series arrangement. This Parallel/Series arrangement allows for the use of AC power sources at voltage potentials much higher than the drop across an individual OLED and is tolerant to a short failure across one or more of the OLEDs in one or more of the groups. The Parallel/Series arrangement suffers however from the problem that an open failure in any one of the OLEDs in a group renders all of the OLEDs in that entire group inoperative. The Parallel/Series arrangement as shown requires tight tolerances in each masking step and is therefore difficult to fabricate.
There is a need therefore for an improved arrangement of OLEDs in a light source that avoids the problems noted above.